Abrading – Machine – Rotary tool
Reexamination Certificate
1998-11-11
2002-03-19
Rachuba, M. (Department: 3724)
Abrading
Machine
Rotary tool
C451S287000, C451S288000, C451S289000, C451S384000, C451S388000, C451S397000
Reexamination Certificate
active
06358129
ABSTRACT:
TECHNICAL FIELD
The present invention relates to backing members for holding microelectronic-device substrate assemblies to a carrier head in mechanical and/or chemical-mechanical planarization processes. More particularly, the present invention relates to backing members that hold a substrate assembly to a carrier head via a vacuum force during planarization of the substrate assembly on a polishing pad.
BACKGROUND OF THE INVENTION
Mechanical and chemical-mechanical planarizing processes (collectively “CMP”) are used in the manufacturing of microelectronic devices for forming a flat surface on semiconductor wafers, field emission displays and many other microelectronic-device substrate assemblies. CMP processes generally remove material from a substrate assembly to create a highly planar surface at a precise elevation in the layers of material on the substrate assembly.
FIG. 1
schematically illustrates an existing web-format planarizing machine
10
for planarizing a substrate assembly
12
. The planarizing machine
10
has a support table
14
with a top panel
16
at a workstation where an operative portion (A) of a polishing pad
40
is positioned. The top panel
16
is generally a rigid plate to provide a flat, solid surface to support the operative section of the polishing pad
40
during planarization.
The planarizing machine
10
also has a plurality of rollers to guide, position and hold the polishing pad
40
over the top panel
16
. The rollers include a supply roller
20
, first and second idler rollers
21
a
and
21
b
, first and second guide rollers
22
a
and
22
b
, and a take-up roller
23
. The supply roller
20
carries an unused or preoperative portion of the polishing pad
40
, and the take-up roller
23
carries a used or post-operative portion of the polishing pad
40
. Additionally, the first idler roller
21
a
and the first guide roller
22
a
stretch the polishing pad
40
over the top panel
16
to hold the polishing pad
40
stationary during operation. A drive motor (not shown) drives at least one of the supply roller
20
and the take-up roller
23
to sequentially advance the polishing pad
40
across the top panel
16
. As such, clean preoperative sections of the polishing pad
40
may be quickly substituted for used sections to provide a consistent surface for planarizing the substrate assembly
12
.
The web-format planarizing machine
10
also has a carrier assembly
30
that controls and protects the substrate assembly
12
during planarization. The carrier assembly
30
generally has a carrier head
31
with a plurality of vacuum holes
32
to pick up and release the substrate assembly
12
at appropriate stages of the planarizing cycle. A plurality of nozzles
41
attached to the carrier head
31
dispense a planarizing solution
42
onto a planarizing surface
43
of the polishing pad
40
. The carrier assembly
30
also generally has a support gantry
34
carrying a drive assembly
35
that translates along the gantry
34
. The drive assembly
35
generally has actuator
36
, a drive shaft
37
coupled to the actuator
36
, and an arm
38
projecting from the drive shaft
37
. The arm
38
carries the carrier head
31
via another shaft
39
such that the drive assembly
35
orbits the carrier head
31
about an axis B—B offset from a center point C—C of the substrate assembly
12
.
Many planarizing machines also use a substrate backing member
50
in the carrier head
31
to support a backside of the substrate assembly
12
. The backing member
50
is typically a perforated, flexible pad positioned between the carrier head
31
and the substrate assembly
12
. The perforations through the backing member
50
are generally a plurality of uniform pores or holes (not shown) that directly transfer a vacuum force from each vacuum hole
32
in the carrier head
31
to a backside
15
of the substrate assembly
12
. In operation, the vacuum force is drawn against the backside
15
of the substrate assembly
12
through the perforated backing member
50
to pick up the substrate assembly
12
from a load station (not shown) or the polishing pad
40
.
The polishing pad
40
and the planarizing solution
42
define a planarizing medium that mechanically and/or chemically-mechanically removes material from the surface of the substrate assembly
12
. The web-format planarizing machine
10
typically uses a fixed-abrasive polishing pad having a plurality of abrasive particles fixedly bonded to a suspension material. The planarizing solutions used with fixed-abrasive pads are generally “clean solutions” without abrasive particles because additional abrasive particles in conventional abrasive CMP slurries may ruin the abrasive surface of fixed abrasive pads. In other applications, the polishing pad
40
may be a nonabrasive pad composed of a polymeric material (e.g., polyurethane), a resin, or other suitable materials without abrasive particles. The planarizing solutions
42
used with nonabrasive polishing pads are typically “abrasive” CMP slurries with abrasive particles.
To planarize the substrate assembly
12
with the planarizing machine
10
, the carrier assembly
30
presses the substrate assembly
12
against the planarizing surface
43
of the polishing pad
40
in the presence of the planarizing solution
42
. The drive assembly
35
then orbits the carrier head
31
about the offset axis B—B to translate the substrate assembly
12
across the planarizing surface
43
. As a result, the abrasive particles and/or the chemicals in the planarizing medium remove material from the surface of the substrate assembly
12
.
CMP processes should consistently and accurately produce a uniformly planar surface on the substrate assembly
12
to enable precise fabrication of circuits and photo-patterns. For example, during the fabrication of transistors, contacts, interconnects and other components, many substrate assemblies develop large “step heights” that create a highly topographic surface across the substrate assembly
12
. To enable the fabrication of integrated circuits with high densities of components, it is necessary to produce a highly planar substrate surface at several stages of processing the substrate assembly
12
because non-planar substrate surfaces significantly increase the difficulty of forming submicron features. For example, it is difficult to accurately focus photo-patterns to within tolerances of 0.1 &mgr;m on nonplanar substrate surfaces because submicron photolithographic equipment generally has a very limited depth of focus. Thus, CMP processes are often used to transform a topographical substrate surface into a highly uniform, planar substrate surface.
In the competitive semiconductor industry, it is also highly desirable to have a high yield of operable devices after CMP processing by quickly producing a uniformly planar surface at a desired endpoint on a substrate assembly. For example, when a conductive layer on the substrate assembly
12
is under-planarized in the formation of contacts or interconnects, many of these components may not be electrically isolated from one another because undesirable portions of the conductive layer may remain on the substrate assembly
12
. Additionally, when a substrate assembly
12
is over-planarized, components below the desired endpoint may be damaged or completely destroyed. Thus, to provide a high yield of operable microelectronic devices, CMP processing should quickly remove material until the desired endpoint is reached.
One manufacturing concern of CMP processing is slippage between the substrate assembly
12
and the carrier head
31
during planarization. Such slippage is problematic because displacement between the substrate assembly
12
and the carrier head
31
during planarization may crack the substrate assembly
12
, damage individual devices, or produce inconsistent planarizing results that cause localized under-planarization or over-planarization on the substrate assembly
12
.
Existing techniques to inhibit or prevent slippage between the substrate assembly
12
and the
Dorsey & Whitney LLP
Micro)n Technology, Inc.
Rachuba M.
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